java - How to use dagger in a android library project

Question

I'm currently trying to add Dagger to my android projects. For the apps projects its easy and clear to me, how to build the ObjectGraph. But I dont quite know whats the best way to do this in my android library projects.

Should I keep building the ObjectGraph in the Application class of the apps and pass the OG over to a LibraryModule - plussing the OG of library to the Apps OG? Or should i build the whole ObjectGraph in the library?

What if I need to inject a class in the library by ObjectGraph.inject(this)? In my Apps projects I can get the OG from the Application class. But how to handle this in the library? Should I add a @Provides method for the ObjectGraph?

Big thanks for your help.

Edit: In short: How can I call ObjectGraph.inject(this) in my library project where I don't have access to the OG because it is being builded in the Application Class?

Answer 1

In case someone using Dagger 2 gets here, this is the way I've done in my App:

In the library module I've created the following Module and Component:

@Module
public class ModuleUtil {

    @Provides
    public RestTemplate provideRestTemplate() {
        return new RestTemplate();
    }

}

@Singleton
@Component(
        modules = {
                ModuleUtil.class
        })
public interface MainComponent {
    void inject(Postman postman);
}

And then I've created the Singleton below in order to manage the injections:

public class DaggerWrapper {

    private static MainComponent mComponent;

    public static MainComponent getComponent() {
        if (mComponent == null) {
            initComponent();
        }
        return mComponent;
    }

    private static void initComponent () {
       mComponent = DaggerMainComponent
                .builder()
                .utilModule(new ModuleUtil())
                .build();
    }
}

When some class from the library module needs to inject its members, I simply call DaggerWrapper.getComponent().inject(this); and that't it.